This invention relates to an airbag for shoes and particularly to an airbag which contains mechanical cushion members to provide long life and to provide support if the airbag should become punctured.
Airbags are commonly placed in the soles of sneakers to cushion the bottoms of the user""s feet from the impact of running or walking. However, airbags do not provide sufficient cushioning for high loads and can lose their cushioning effect after repeated use. In co-pending application Ser. No. 29149621, now U.S. Design Patent D460854 resiliently flexible, cylindrical cushion members are placed in an airbag at spaced-apart locations. The cushion members are held in their desired locations by a stiffer flexible connecting plate, and the cushion members and the connecting plate are enclosed in a flexible casing. The cushion member, connecting plate and casing, are all made from a plastic material and are cast together to form an integral unit. While this type of airbag is an improvement over the previous airbags, if the cushion members are stiff enough to give adequate cushioning at high loads, they are too stiff at light loads or during the initial stages of loading.
The airbag of the subject invention overcomes this problem by placing spiral grooves around the periphery of the cushion members to give them a spring-like structure. This allows the cushion members to be less stiff under light or initial loading and still have sufficient stiffness to provide the necessary cushioning effect at higher levels of loading.